1. Field of the Invention
The present invention relates to a curved suspended ceiling having a grid of inverted T beams suspended from a structural ceiling, with drywall boards fastened to the grid.
2. Description of the Prior Art
Suspended ceilings in rooms are common. They have a grid of metallic beams that is suspended from an overhead structural ceiling, as by wires.
The metallic beams used in the grids of suspended ceilings are made in a continuous process, wherein a continuous strip of metal, usually steel, fed off a reel, is continuously and sequentially passed through a series of rolls that form the metal into an inverted T cross section having a web, a bulb at the top of the web, and horizontal flanges extending from the bottom of the web. Such beam construction is well-known.
A straight, finished beam continuously emerges from the roll forming operation, and is cut, on the run, into suitable lengths, of, for instance, 12 feet, or 4 feet, or 2 feet, with, for instance, a flying shear. Connectors are then formed at the ends of the straight beam lengths. The beams are then stacked and packaged for shipment to the job site for assembly into the grid of a flat, horizontal suspended ceiling. The beam cross section gives the beam rigidity throughout these operations.
The beams are formed into a grid at the job site, in the well-known prior art manner, by means of the connectors at the ends of the beam.
In a panel suspended ceiling, panels are laid in the grid openings and supported by the flanges of the beams. In a drywall suspended ceiling, drywall boards are attached to the beams of the grid by screws.
Both types of ceilings described above extend in a horizontal plane. Virtually all suspended ceilings are horizontal.
Occasionally, suspended ceilings that are curved are installed, particularly of the drywall type. In a curved drywall suspended ceiling, a grid of curved beams is suspended by wires from a structural ceiling, and drywall panels then are attached to the grid by screws, as in a horizontal drywall suspended ceiling. The faces of the drywall panels are wetted and then are bent to the desired shape prior to attachment to the grid.
In one form of curved drywall suspended ceiling, the grid is formed of straight beams that are curved into facets to form the desired radius, at the job site. This involves forming facets by slitting, as with shears, the bulb and web of each beam, normal to the length of the beam, at, for instance, 8 inch spaced intervals, resulting in 8 inch facets, at the job site, and bending the beam at each slit, between facets, to the desired radius. Clips are then affixed over the slits to fix the curve. This requires a custom operation at the job site that is time-consuming, since the slits are located and made, and the clips attached, individually. The work is done at the site since the beams, after being slit, and before the clips are attached, are very flimsy and cannot be handled in the traditional way of uncut, straight beams. Straight unslit beams are stacked, shipped, and installed, as relatively rigid pieces. In slitting the beams through the bulb and web, the beam effect is destroyed, not to be restored until the clips are installed.
Another form of curved drywall ceiling is shown in U.S. Pat. No. 6,047,512, wherein the grid beams are pre-formed and pre-engineered into true curves at the factory. Pre-engineered sections have integral webs that have no web cuts, but are curved at the factory into various radii. This requires an inventory of various sizes and shapes, which are custom assembled at the job site, or at the factory, in a time-consuming and intricate procedure.
In the present invention, straight, inverted T beams are continuously roll formed from strip metal, at the factory, in the usual prior art way. Such beams are of inverted T cross section with a bulb at the top, a downward extending vertical web, and horizontal flanges extending from the bottom of the web. The two layers of the web are continuously stitched together.
The present invention permits the above prior art straight beams to be efficiently converted into curved beams. Cutouts in the beam, at spaced intervals along the beam, are made continuously and contemporaneously with the roll forming operations, in a portion of the web and a bulb. A segment of the bulb is left in place above the cutout to maintain the integrity of the straight beam. The cutouts do not impair the beams"" integrity during handling and shipping to the job site. The cutouts are manually extended through the remaining segment of the bulb at the job site with a minimum of cutting and no need for measuring, and the beam is bent to the required radius, at the cutouts, between facets. Splice plates are applied over the extended cutouts at the bend to fix the beam at the desired faceted curve.
The cutouts are continuously and simultaneously made in the beam, for instance at 8, 16, or 24-inch intervals, as the beams are being continuously roll formed in the usual prior art roll forming operation. No manual effort is required in forming these cutouts. The preferred form of cutout has a V-shape at the bottom, with upwardly extending arms from the sides of the V. There is left a segment of the bulb, in the beam, at the top of the cutout, along with a portion of the web left at the bottom of the cutout, which is sufficient to maintain integrity of the straight beam during the cutting of the continuous moving beam into beam lengths, the forming of the connectors at the end of the lengths, the shipping to the job site, and the handling at the job site. At the job site, the bulb segment remaining in the beam above the cutouts, between facets, is snipped, for instance, with shears to permit the beam to be bent, between facets, into a faceted, convex or concave radius, and splice plates are applied at the cutouts by screws to fix the beam in this faceted radius.
The invention eliminates the need for an inventory of factory precurved beams, of different radii and different sized segments, that are subsequently assembled and fixed at the job site, as in one form of curved suspended ceiling in the prior art, or for time-consuming slitting, and fashioning, from an integral, straight beam, into a faceted curved beam, at the job site, as in another form of curved suspended ceiling in another form of prior art.